Boron-Doped Diamond Sensors for Neurotransmitter Detection: Fabrication and Characterization

Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
M. Becker, C. A. Rusinek (Fraunhofer USA, Inc.), B. Fan, W. Li, Y. Guo (Michigan State University), and R. Rechenberg (Fraunhofer USA, Inc.)
In vivo neurotransmitter sensing has developed into a significantly prominent field over the course of the past two decades. With biocompatibility and ease of miniaturization, electrochemical methods are a powerful tool for these measurements. This has largely been completed with carbon fiber microelectrodes where several analytes such as dopamine and serotonin have been detected at very low levels. However, carbon fiber electrodes can be prone to fouling and thus, boron-doped diamond (BDD) has emerged as a material capable of long-term reliability and stability. While, BDD-coated tungsten (W) wires have been used for in vivo dopamine detection in mouse brains, a remaining issue is the significant difference in Young’s modulus from BDD (»1000 GPa) and that of brain tissue (103- 105 GPa). The strain between a rigid implant and soft tissue has been thought to be a cause of irreversible tissue damage and negative immune response. Hence, a flexible material is desired to prevent such damage from occurring and polymer-based neural implants have shown promise as a possible implantable device. Though BDD is unable to be deposited directly on a polymer substrate, we developed a wafer transfer process from BDD on silicon (Si) substrates to flexible Parylene-C substrates (an FDA-approved and USP Class VI biocompatible polymer). The fabricated sensors included BDD working, reference and counter electrodes and were characterized using several analytes including Ferricyanide (Fe(CN)63/4-), Ruthenium hexaaamine (Ru(NH3)62+/3+), and dopamine. Fast scan cyclic voltammetric (FSCV) and chronoamperometric measurements of dopamine were completed as well. These novel fabricated BDD sensors on Parylene-C open a new avenue of electrochemical-based neurotransmitter sensing with potential in vivo measurement capability.